Apparatus for cleaning film

ABSTRACT

An ultrasonic film cleaner has an enclosed shell within which is provided an internal solvent recovery system for recapturing solvent stripped from the ultrasonically cleaned film. The recovered solvent is recirculated to fluid nozzles which add solvent to a cleaning tank to skim dirty solvent over a spillway into an offset boiling tank, where contaminates precipitated to avoid build up of contamination in the solvent bath. An air filtration and recirculation system is provided to maintain a dust free environment within the shell. The film transport mechanism preferably has rolls with snap-on mountings for ease in adapting the cleaner for various width films.

United States Patent 1191 Miller. et al.

[ APPARATUS FOR CLEANING FILM [75] Inventors: Arthur J. Miller, Fort Lee, N.J.;

, 4 Raymond Perkins, Plainville; Harold E. Sullivan, East Hampton, both of 1 June 12, 1973 Primary Examiner-Richard E. Moore Conn Attorney-John M. Prutzman, Donald J. Hayes, Vernon Assignees; Jerome B. Gracey, Hartford; Kalb, Chilton, James and 1 1 ygm n ugr ieumx gheeiqkm Rene/"1th both of Conn; part interest to each 22] Filed: July 3, 1969 [57] I ABSTRACT An ultrasonic film cleaner has an enclosed shell within Appl- 838,760 which is provided an internal solvent recovery system for recapturing solvent stripped from the ultrasonically 52 us. C1. 15/100, 15/302, 134/9, cleaned film The recovered Solvent is recirculated 134/64 fluid nozzles which add solvent to a cleaning tank to [51 Int. Cl. B08b 7/02 skim dirty Solvent Over a p y into an Offset boiling [58] Fieldof Search 134/1, 9, 15, 64, tankrwhel'e contaminates Precipitated to avoid build 134/122, 90, 107, 108; 15/302, 306, 307, 100, up of contamination in the solvent bath. An air filtra- 4 tion and recirculation system is provided to maintain a dust free environment within the shell. The film trans- 5 References Cited port mechanism preferably has rolls with snap-on UNITED STATES PATENTS mountings for ease in adapting the cleaner for various th fl 3,158,886 12/1964 Grimes 134/64 x 3,070,463 12/1962 Barday 134/64 X 11 Claims, 8 Drawing Figures i -:5 1521' 1" "'i:". l e1l '11: i 1; "ll h 5: I 54. 2=-=-.-' l= ==-..=1w-Li -=v.-= mia'v-n'u'v-rlr'gi z u i p162 20 2o I E [2:23:33 i/ l2-: l2 I 22 1 1 1 I i |50"-r- F INVENTORS ARTHUR J. MILLER RAYMOND PERKINS HAROLD E. SULLIVAN BY ,1" ,BM, W ATTORNEYS PAIENm; JUNI 2 m5 sum 1 or 5 as. I

PAT ENIEI] JUN 1 2197s SHEET 2 BF 5 FIG. 2

INVENTORS ARTHUR J. MILLER RAYMOND PERKINS HAROLD E. SULLIVAN BYW IMfiM ATTORNEYS PATENHDJun 1 2m;

SHEET 3 [IF 5 FIG. 3

INVENTORS ARTHUR J. MILLER RAYMOND PERKINS HAROLD E. SULLIVA N ATTORNEYS PATENTEUJUH121975 SHEET U [1F 5 FIG. 4

INVENTORS ARTHUR J. MILLER RAYMOND PERKINS HAROLD E. SULLIVAN a a. "P

,ema, MW

ATTOR NEYS APPARATUS FOR CLEANING FILM BACKGROUND OF THE INVENTION This invention relates generally to the cleaning of photographic films and the like and is more particularly directed to an improved apparatus for ultrasonically cleaning strips of motion picture film, magnetic and video tapes and similar strip materials.

The well known tendency of the inherently soft surfaces of a photographic film to pick up dust particles, grease, and other foreign matter presents a continuous problem in the preparation of motion picture films wherein the single original film must be copied to produce several hundred exhibition copies of the film.

During the copying process, several direct copies are made from the original film and the exhibition copies are normally made by copying the direct copies. Any foreign matter on the. film being copied is magnified during the copying procedure to produce undesirable blurred areas or spots on the copy negative.

Moreover, as a film is unwound and rewound, it becomes electrically charged and will pick up dust and dirt from the atmosphere. As the film is rewound, the winding tensions will cause the collected dirt trapped between adjacent windings of the reel to scratch the soft film surfaces, particularly the image carrying emulsion coated surface. Such scratches also result in imperfections on the copy produced. It is, therefore, necessary to clean a film periodically during the copying process to insure that marketable exhibit copies are produced to protect the high investment represented by the original.

In the devices heretofore known using an ultrasonically agitated solvent to clean films,'two sources of impurities hinder cleaning efficiency. The first source of impurities are those removed from the film which remain in the solvent to progressively contaminate the solvent bath. The second source of impurities is the atmosphere from which the film accumulates dust after it leaves the ultrasonic cleaning chamber and as it is rewound on the take-up reel.

Another undesirable feature of prior art film cleaners is that expensive external ducts and solvent recovery apparatus are frequently required to recover the cleaning solvent stripped from the film. The economic feasibility of employing external solvent recovery apparatus depends, of course, on the volume of solvent evaporated and the cost of the recovery equipment. In practice, it has been found that only those installations using several film cleaners are able to recoup the cost of external recovery apparatus in recovered solvent, while installations having a lesser volume of use incur an increased operating expense in the form of lost solvent. It is, therefore, highly desirable to provide a film cleaner with an internal solvent recovery apparatus without greatly increasing the cost of the machine.

An additional undesirable feature of previous film cleaners is that the film transport mechanisms therein cannot be readily adapted for accommodating different width films.

SUMMARY OF THE INVENTION In accordance with Applicants invention, a film cleaner is provided with an enclosed shell. Within the shell are mounted an ultrasonic cleaning unit, evaporative and preferably mechanical stripping means, an air filtering and recirculating system and a solvent recovery system. The film is guided by a film transport merchanism sequentially from a feed reel, through an ultrasonic cleaning tank where it is cleaned, preferably past spray nozzles where a spray of clean solvent rinses dirty solvent from the film, through the drying chamber where solvent is stripped from the film preferably by stripping rolls, after which it is evaporatively dried by a flow of filtered heated air and then wound on a takeup' reel.

Substantially all of the stripped solvent is returned to the cleaning tank through an internal solvent recovery system to significantly reduce the operating expense of the device by minimizing the amount of'make-up solvent required.

The cleaning tank is provided with means for continually skimming contaminated solvent from the cleaning tank into a boiling tank wherein the contaminants may be precipitated as the solvent vaporizes to avoid progressive contamination of the solvent bath, whereby cleaning efficiency is enhanced.

Moreover, filtered air is recirculated throughout the enclosed shell and through the drying chamber to insure a dust-free environment that also increases cleaning efficiency.

A further feature of this invention is the provision of a snap-on mounting means for the rolls of the film transport mechanism to allow facile interchangability of various sized rolls so that the cleaner may be rapidly adapted for cleaning different width films.

It is accordingly an object of this invention to provide an ultrasonic strip material cleaner having an internal solvent recovery system capable of recovering substantially all solvent stripped from the processed material.

Another object of the invention is to provide an ultrasonic film cleaner in which cleaning is performed in a decontaminated environment.

It is a further object of the invention to provide an ultrasonic film cleaner in which contaminants are continuously removed from the solvent bath.

A still further object of the invention is to provide a strip material transport mechanism with rolls having snap-on mountings for rapid and easy mounting and dismounting of the rolls.

These objects and other objects, features and advantages of the present invention will become apparent as the description proceeds with reference to the drawings wherein:

FIG. I is a front elevation of the preferred embodiment of an apparatus according to the invention;

FIG. 2 is a side elevation of the apparatus shown in FIG. I with the right wall of the shell broken away;

FIG. 3 is a perspective view of the ultrasonic cleaning unit employed in the preferred embodiment;

FIG. 8 is a sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a sectional view taken along line 55 of FIG. 3;

FIG. 6 is an exploded side elevation illustrating the snap-on mounting provided for the rolls of the film transport;

FIG. 7 is a side elevation of a roll for wider film which has the same snap-on mounting as that shown in FIG. 5; and

FIG. 8 is a section of the safety roll assembly.

the drawings wherein like reference numerals are used to identify the same elements in the various views. It

should be understood that the invention may be used to clean strip materials other than motion picture film as described, such as magnetic and video tapes and the like.

Referring initially to FIGS. 1 and 2', a cleaner has a rectangular shell 12 which surrounds the sides of the apparatus. A vertical mounting panel 14 secured within the shell 12 intermediate its front and rear edges divides the cleaner into two general compartments, a forward enclosed cleaning compartment 16, wherein the cleaning elements hereinafter discussed are mounted, and a rear compartment 18 wherein the electrical and mechanical accessories needed to actuate the film transport are mounted. The cleaning compartment 16 is sealed to the ambient atmosphere by glass doors 20 mounted on the forward edge of the shell 12 upon hinges 22 and a forward cover plate 23 which is broken away to expose the elements mounted in the lower portion of thecleaning compartment.

Positioned within one side of the cleaning compartment 16 are a feed reel 24 for dirty film 26 mounted on a feed reel shaft 28 secured to the mounting panel 14 and a take-up reel 30 mounted on a driven take-up shaft 32, the latter shaft also being secured to the mounting panel 14.

Briefly following the travel of the film through the cleaning compartment 16, the film 26 passes from the feed reel 24 over a guide roll 34 downward into an ultrasonic cleaning chamber 36 provided in the bottom portion of an ultrasonic cleaning unit 38. The ultrasonic cleaning chamber 36 contains an appropriate liquid solvent bath 40 which is ultrasonically agitated in a conventional manner by transducers 42 and 44 to effectively clean the film 26 as the film passes horizontally through the cleaning chamber 36 over frame guide rolls 46 and 48. On exiting from the solvent bath 40, the emulsion and base sides of the film 26 are preferably rinsed by a flow of clean solvent emanating from a pair of spray nozzles 50 and 52. The rinsed film is then passed upward through a chilling chamber 54 to a drying chamber 56 where' the liquid solvent superficially adhering to the film is stripped. Two stripping means are shown. The first means is a pair of soft fiber-surfaced stripping rolls 58 and 60 rotatably mounted within the drying chamber, which rolls are accurately spaced on each side of the film 26 so as to lightly contact the film. The stripping rolls 58 and 60 are preferably Dacron fiber plush rollers of the type developed by Eastman Kodak Company. By rapidly rotating the stripping rolls against the flow of the film 26 in the direction indicated, say at 3,000 rpm, some of the liquid solvent is mechanically brushed from the film without causing damage thereto. The remainder of the liquid solvent is evaporatively stripped by a downward flow of heated, dust-free air. To avoid film damage the film 26 should be completely dry before it passes over a first drying chamber roll 62 mounted within the drying chamber 56. Such stripping may be accomplished solely evaporatively without the stripping rolls 58 and 60 by lengthening the distance between the nozzles 50 and 52 and the first drying chamber roll 62, increasing the temperature and flow rate of the drying air and/or by decreasing the film feed rate. We prefer to mechanically strip a portion of the adhering solvent with the stripping rolls 58 and 60 to avoid increasing either the length of the drying cham ber 56 or the heat transfer requirements necessary to recover evaporated solvent for processing film at high speed.

The dried film then passes over the roll 62 downward under a second drying chamber roll 64 and then up ward out of the drying chamber 56 over a film drive roll 66 under a safety roll 68 and then under a conventional tension control arm 70 to the take-up reel 30. The mounting of the reels 24 and and the rolls 34, 46, 48, 62, 64, 66 and 68 (hereinafter collectively referred to as the film transport mechanism) will be described in greater detail below. A U-shaped shield 71 is provided under the second drying chamber roll 60 to shield the dry film from any solvent splashing up from the stripping rolls.

The structure of the ultrasonic cleaning unit 38 is best seen in FIGS. 3, 4 and 5 and generallycomprises the lower cleaning chamber 36 and the larger chilling chamber 54 positioned above and symmetrically about the cleaning chamber 36. The upper edges 72 of the cleaning chamber walls 74 extend into the lower por tion of the chilling chamber 54 and the lower portion of the chilling chamber walls 76 have inward turning depending flanges 78 which are secured to the cleaning chamber walls 76 to form a solvent collecting trough 80. An upper and lower set of chilling chamber cooling coils 82 and 84 respectively, are secured to the inner sides of the chilling chamber walls 76 directly above the solvent collecting trough 80.

A solvent recovery chamber 86 is disposed externally around and secured to two sides of the chilling chamber 54. The solvent recovery chamber 86 receives the drying air passing through the drying chamber 56 through an inlet port 88 and passes the drying air through a series of baffles 90 over cooling fins 92 to an outlet port 94. A deflector plate 96 (see FIG. 1) is provided to deflect most of the vaporous solvent laden drying air and the liquid solvent brushed from the film 26 into the inlet port 88. The vaporous solvent evaporated from the film 26 in its passage through the drying chamber 56 is condensed from the drying air by the cooling fins 92 and falls to the bottom of the solvent recovery chamber together with the brushed off liquid solvent. The solvent-free drying air exiting through the outlet port 94 is recirculated through the apparatus in the manner hereinafter described. The'recovered solvent passes through a drain conduit 98 interconnecting the bottom of the solvent recovery chamber 86 with a solvent reservoir 100 secured to the exterior of the cleaning chamber 36, which reservoir also contains cooling coils 102.

An offset boiling tank 104 provided with conventional heaters 106 is positioned adjacent the cleaning chamber 36 and is in fluid communication therewith through an aperture 108 feeding into the upper portion of the cleaning chamber. Solvent vapor enters the cleaning compartment through the aperture 108 and forms a vapor blanket above the surface of the solvent bath 40 in the chilling chamber 54. The height of the vapor blanket is controlled by the cooling coils 82 and 84 which condense the vapor and cause it to drop into the solvent collecting trough 80, from whence it passes to the solvent reservoir 100 through a drain conduit 110 (FIG. 5). The temperature of the chilling chamber cooling coils should preferably maintain the vapor blanket at a height intermediate the cooling coils 82 and 84 so that no solvent leaks into the remainder of the cleaning chamber. The cooling coils 82 and 84 also condense vaporous solvent from any drying air not defiected into the inlet port 88 of the solvent recovery chamber 86, while stray brushed-off solvent falls either into the solvent bath 40 or the collecting trough 80.

There are thus two sources of solvent for the reservoir 100, the solvent recovered in the recovery chamber 86 and solvent vaporously emanating from the boiling tank 104 which is condensed in the chilling chamber 54 and collected in the collecting trough 80. A portion of the condensed solvent is circulated from the reservoir to the cleaning tank through flexible piping 112 to the suction side of a pump P and hence from the pressure side of the pump P to the spray nozzles 50 and 52, via piping 114, which nozzles serve the primary function of adding make-up solvent to the solvent bath 40 while also rinsing the film. The remainder of the condensed solvent passes to the boiling tank 104 through conduit 116 for recirculation as described above. The apparatus, therefore, incorporates an internal solvent recovery system that recovers in excess of 90 percent of the solvent stripped from the film.

Any water present in the solvent or drying air floats to the top of the solvent in the reservoir and passes out the U-shaped water drain 118. The solvent level in the boiling tank 104 is maintained at a predetermined height by a conventional pressure gage 107 provided on the bottom of the tank 104, which gage deenergizes the heaters 106 when the solvent level is too low to avoid boiling the boiling tank dry.

As shown in FIG. 4, the level of the solvent bath 40 in the cleaning chamber 36 is regulated by the lower lip 120 of the aperture 108 which functions as a spillway. The contaminants removed from the film 26 remain on the top of the bath 40 in either dissolved or undissolved form and continuously spill over into the boiling tank as solvent is added by the nozzles 50 and 52. As the solvent is vaporized the impurities precipitate to the bottom of the boiling tank 104, from whence they may be periodically removed through a removable clean-out door 122. Thus impurities are continuously removed from the recycled solvent. If desired, a filter may be placed in conduits 112 and 114 to further insure that the solvent in the cleaning chamber 36 is clean.

The chilling chamber cooling coils 82 and 84, solvent recovery chamber cooling fins 92 and reservoir cooling coils 102 are sequentially supplied in a conventional manner with an appropriate refrigerant through conduits 124 to preferably maintain the upper cooling coils 82 at 35 40 F so as to achieve maximum condensation while avoiding frosting, with the remaining cooling elements maintained at temperatures lower than the boiling point of the solvent.

With reference once again to FIGS. 1 and 2, ultrasonic energy is supplied the transducers 42 and 44 from a conventional ultrasonic generator 126 in a conventional manner.

The upper immersible transducer 42 and the frame rolls 46 and 48 are mounted on a frame 128, which frame has appropriate bearings that slidably engage vertical slide rods 130 and 132 secured to the mounting panel 14. The frame 128 also has a vertical toothed rack 134 which meshes with a pinion 136 mounted on the drive shaft of a slide motor 138, the latter being mounted on an appropriate bracket 140 in the rear compartment 18. The travel of the frame 128 on the slide rods 130 and 132 is accurately controlled by microswitches 142 and 144 which are connected to the slide motor 138 through appropriate circuitry to deenergize the slide motor when tripped by the frame. The lower microswitch 144 should be positioned so that when the frame 128 is lowered into the ultrasonic cleaning unit 30 during cleaning (FIG. 1), the frame rolls 46 and 48 guide the film horizontally between the transducers at the optimum distance for cleaning. The upper microswitch 142 should, of course, be positioned so that the frame 128 may be raised sufficiently to allow easy access to the frame rolls for threading. The drying chamber 56 also has a hinged door 146 to give access to the stripping rolls 58 and and the drying chamber rolls 62 and 64 for threading.

The description will now proceed to the air circulation and filtration system provided to recirculate dustfree air throughout the cleaning compartment. A blower 148 located in the bottom of the cleaning compartment 16 forces air through an air supply duct 150 which runs along the bottom and up one side of the cabinet to feed into an enclosed plenum 152 at the top of the cleaning chamber. From the plenum 152 the air passes through absolute filters 154 which filter it to 0.5 microns with a greater than 99 percent efficiency to render it substantially dust-free. The filtered air is then divided into two streams. One stream, indicated by arrows 156, passes through a perforated covering plate 158, downwardly over the take-up and feed reels 30 and 24 to insure that the film 26 is processed in adecontaminated atmosphere. The air flow 156 passes back to the suction side of the blower 148 through return duct 160 for recirculation.

Another stream of air as indicated by arrows 162 passes through the filters 154 into a heating chamber 164 through a cut out portion 159 of the perforated plate 158 where it is heated by conventional heater 166 to a predetermined drying temperature. The heated air then passes to the drying chamber 56 in a flow counter to the direction of film travel to evaporatively strip solvent from the film. The solvent laden drying air then enters the solvent recovery chamber 86 through the inlet port 88, and, after solvent has been condensed therefrom, the drying air flow 162 passes from the outlet port 94 to the blower 148 via a drying air return duct 168 for recirculation through the cleaner.

In practice, we have found it desirable to deliver approximately l cfm of air from the blower 148 to the plenum 152 at 6 inch static pressure. The drying air flow 162 is preferably about cfm and the reel air flow 148 should be about 75 cfm. Regulation of the division of air flowing from the plenum can, of course, be accomplished by appropriate design of the perforated cover plate 158 and cut out portion 159 thereof.

The drying air flow 162 should be heated by the heater 166 to a temperature greater than the boiling point of the solvent used but should not be so great as to cause the film to curl or otherwise become distorted. We have found that for use with the preferred type of solvent described below, an air temperature in the range of l30 to F is satisfactory.

The preferred type of solvent for use in the cleaner is one with a relatively low boiling point to facilitate recovery in the solvent recovery chamber 86, one which does not attack either the materials from which the cleaner is constructed or the strip material being cleaned, and yet one which will effectively clean the strip material when subjected to ultrasonic energy. An example of such a solvent is an azeotropic mixture of 88 percent trichlorotrifluoroethane and 12 percent ethanol which boils at about 115 F, is an effective cleaning solvent and does not attach standard construction materials such as stainless steel, aluminum, brass and nylon. The high specific gravity of this solvent also effectuates skimming of contaminants from the solvent bath 40 into the boiling tank 96 and separation of water from the solvent in the reservoir 100 because water and contaminants float in the solvent. It should be appreciated that the above-mentioned solvent is only an example of a solvent capable of satisfactory use with the invention, and other solvents having similar properties may be used as well.

With reference now to FIG. 2, the film is driven through the cleaner by the drive roll 66 which is mounted on the drive shaft 170 of a film-motor 172. The film motor 172 is secured in the rear compartment 18 to the mounting panel 14 upon an appropriatev bracket 174 with its drive shaft 170 passing through the mounting panel14.

To insure a uniform tension in the film an electrical pot 176 is secured to the feed reel shaft 28 to produce a minimum drag' so that the feed reel 24 doesnot coast as its speed of rotation accelerates due to the constant rate of film removed while the diameter of reeled film decreases. On the other hand, the take-up reel must rotate at progressively decreasing velocity to accommodate a constant take-up film while the diameter of the reeled film increases. To this end, the take-up reel shaft 32 is driven by a take-up motor 178 mounted in the rear compartment 18 on bracket 180 through an electrical clutch 182 and brake 184. An electrical pot 186, also positioned on the shaft 32, actuates the brakes 184 and clutch 182 to insure that the torque on the take-up reel shaft 32 is constant by causing the electrical clutch 174 to slip more and more at the reeled film diameter increases.

The stripping rolls 58 and 60 are mounted on rotatable shaft which shafts pass through the mounting panel 14 where a pair of meshed pinion gears are mounted thereon. One of the shafts is driven directly by a stripping roll motor mounted to the rear of the mounting panel 14 upon an appropriate bracket, with the intermeshing of the gear pair providing the requisite counter-rotation for the other shaft. The driving means for the stripping rolls is well known to those skilled in the art and it is therefore believed that further illustration is not necessary.

The safety roll 68 is mounted on a non-rotating shaft 188 which is pivoted within a housing 190 secured to the mounting panel 14. An actuating rod 192 is slidably mounted through the panel 14 and is secured to the shaft 188 in a conventional manner to reciprocate horizontally in response to pivoting of the shaft 188 so that when the film 26 passing under the roll 68 is tensioned, the shaft 188 is horizontal and the rod 192 depresses a microswitch 194. The energizing circuitry for the drive motor 172, the take'up motor 178 and the stripping rolls motor is coupled through the microswitch 194,

which motors will operate only when the switch 194 is depressed. If the film 26 breaks during cleaning, the upward pressure on the safety roll 68 will be released to cause the shaft 188 to pivot, whereby the microswitch 194 will be released to deenergize the film transport.

A feature of the present invention is that provision is made for easily changing the elements of the film transport for use with various width films. With reference now to FIG. 6 wherein the assembly for mounting the idler roll 34 is shown in an exploded view, the idler roll 34 is preferably fabricated of Nylon and has a central bore 196 and collar 198 adapted to receive a comple mentary bushing 200, preferably of aluminum or stainless steel. The roll 34 and bushing 200 may be assem bled by passing a set screw or the like through the radial holes 202 and 204, respectively. The bushing 200 has a central bore 206 adapted to fit on a complementary idler 208 and also has a spring loaded ball 210 extending partially into the bore in its rest position. A longitudinal ball guiding groove 212 is formed on the surface of the idler shaft 208 and extends longitudinally from the shaft terminal end 214 to a recessed nest 216 having an appropriate configuration to receive the spring-loaded ball 210, whereby the roller and bushing assembly may be securely mounted on the shaft'208 by merely inserting the bushing and roller assembly onto the shaft with the ball 210 passing along the guide groove 212 until the ball snaps into the nest 216. This mounting process may be reversed to dismount the roll 34 for replacement with a different width roll.

It should be apparent that rolls 34 of various widths may be provided with similar snap-on fittings so that the film transport may be easily converted for processing various width films by merely changing the roll size used. For example, the roll 34 shown in FIG. 6 is for 16mm film while roll 34 shown in FIG. 7 is for 35mm film, which rolls can both be mounted on the same shaft 208 with the same bushing 184. If it is desired to clean wider material such as 3 inch wide video tapes, the shaft 208 and bushing 200 may be elongated accordingly. The width of the stripping rolls 58 and 60 should preferably equal the width of the widest material to be processed by the cleaner 10, for example 3 inches for television video tape.

The shaft 208 is rotatably mounted within a shaft housing 218 on appropriate sealed bearings 220, the housing 218 being secured to the mounting panel 14 as by screws passing through a raised mounting flange 222.

The mounting of the idler roll 34 is shown for illustrative purposes, and it should be understood that the other elements of the film transport (with the exception of the safety roll 68) are similarly mounted on rotatable shafts, either on the mounting panel 14 or the frame 128, as the case may be. Since the safety roll shaft 188 does not rotate axially, bushing 224 of the safety roll 68 (see FIG. 8) has bearings 226 in its outer surface to allow the roll 68 to rotate about the bushing 224, while the bushing 224 may be mounted on the shaft l88 by the interaction of ball 210 and nest 216' in the same fashion as the other film transport elements. A snap ring 228 prevents axial movement between the safety roll 68 and the bushing 224.

It should be understood that the present disclosure is solely for the purpose of illustration and that this invention includes all modifications and equivalents falling within the scope of the appended claims.

terial comprising, in combination:

an enclosed shell defining a cleaning compartment; an ultrasonic cleaning unit including a cleaning chamber containing an ultrasonically agitated solvent bath mounted within said shell;

means for continuously removing contaminants from said solvent bath;

a nozzle positionedabove said solvent bath to add make-up solvent to said solvent bath;

a drying chamber mounted within said shell;

means for mounting feed and take-up reels within said shell;

a strip transport mechanism for sequentially passing a strip of material from said feed reel through said solvent bath for cleaning and through said drying chamber for stripping to said take-up reel;

means for forcing a flow of filtered air heated to a temperature greater than the boiling point of said solvent through said drying chamber to evaporatively strip solvent from said strip;

a solvent recovery chamber mounted within said shell having an inlet adapted to receive said drying air from said drying chamber and an outlet;

refrigerating means disposed within said solvent recovery chamber between said inlet and said outlet to condense and separate said evaporated solvent from said drying air;

means for recirculating said separated solvent back to said nozzle; and

means for continuously forcing a flow of filtered air over said feed and take-up reels.

2. The apparatus of claim 1 in which said means for forcing a flow of heated filtered air through said drying chamber and means for forcing a flow of filtered air over said feed reel and take-up reel comprise:

an air blower mounted within said shell to circulate air therethrough; a filter; conduit means for directing air from the pressure side of said blower to said filter; a heating chamber opening into said drying chamber; means for directing a portion of said filtered air to said heating chamber; means for directing the remainder of said filtered air over said take-up and feed reels; a return duct interconnecting the outlet of said solvent recovering chamber with the suction side of said blower to recirculate said drying air; and

a return duct adapted to direct the air flowing over said reels tothe suction side of said blower for recirculation, whereby a substantially dust-free environment is maintained within said shell by an internally contained air recirculation system.

3. The apparatus set forth in claim 1 in which said means for removing contaminants from said solvent bath comprises:

an offset boiling tank; and

one wall of said cleaning chamber having an aperture therein which is in fluid communication with said boiling tank, the lower edge of said aperture defining a spillway for said solvent bath to allow contaminated solvent to continuously spill over into said boiling tank as clean solvent is added to said solvent bath, whereby contaminants may be continuously precipitated from said solvent as the solvent is vaporized in said boiling tank. 4. The apparatus of claim 3 in which said ultrasonic cleaning unit further includes:

a chilling chamber positioned above said cleaning chamber; refrigerating means secured within said chilling chamber to condense vapor emitted by said boiling v tank; a

a solvent collecting trough positioned within said chilling chamber below said refrigerating means to collect condensed solvent;

a reservoir secured to the exterior of said cleaning tank; and

a conduit interconnecting said collecting trough and said reservoir.

5. The apparatus of claim 4 in which said solvent recovery chamber is secured to the exterior of at least one wall of said chilling chamber, said separated solvent recirculating means comprising:

a conduit interconnecting said solvent recoverychamber and said reservoir;

a conduit interconnecting said reservoir and said boiling tank;

a pump;

a conduit interconnecting said reservoir and the suction side of said pump; and

a conduit interconnecting the pressure side of said pump with said nozzle.

6. The apparatus of claim 5 wherein said drying chamber is positioned above said cleaning chamber which further includes mechanical stripping means mounted in said drying chamber for mechanically stripping liquid solvent from said film, said mechanically stripped solvent falling back into said ultrasonic cleaning unit for recirculation.

7. The apparatus of claim 1 in which said 'strip transport mechanism includes a plurality of rolls, each said roll having a detachable roll mounting assembly comprising:

a ball resiliently secured to the central bore of said roll assembly, said ball extending into said bore in its rest position;

a shaft having a cross-section complementary to said bore, said shaft having a longitudinal ball guiding groove formed therein extending from its terminal end inward to a recessed nest having a configuration complementary to said ball, whereby said roll may be mounted on said shaft by relative movement between said shaft and roll wherein said ball is guided axially along said ball guiding groove until it is resiliently urged into said nest. 8. In an apparatus for cleaning strip material having a cleaning chamber containing an ultrasonically agitated solvent bath, an evaporative drying chamber, and means for sequentially passing the strip therethrough means for forcing a flow of filtered air heated to a temperature greater than the boiling point of said solvent through said drying chamber, means for continuously removing contaminants from said solvent bath which comprises: an offset boiling tank; one wall of said cleaning chamber having an aperture which is in fluid communication with said boiling tank, the lower edge of said aperture defining a spillway for said solvent bath to allow contaminated solvent rinsed from the film to continuously spill over into said boiling tank as solvent is added to said solvent bath, whereby said contami- .chamber having refrigerating means'for condensing solvent vapor in said chamber.

10. The. apparatus of claim 9 in which said apparatus further includes a solvent boiling tank, and means providing a passageway for permitting solvent from the cleaning chamber to flow'to the boiling tank and permitting vaporized solvent from the boiling tank to flow into the chilling chamber.

11. The apparatus of claim 9 in which said refrigerating means is disposed along the interior surface of the chilling chamber and a trough extends along the bottom end of the chilling chamber for collecting condensed solvent.v 

2. The apparatus of claim 1 in which said means for forcing a flow of heated filtered air through said drying chamber and means for forcing a flow of filtered air over said feed reel and take-up reel comprise: an air blower mounted within said shell to circulate air therethrough; a filter; conduit means for directing air from the pressure side of said blower to said filter; a heating chamber opening into said drying chamber; means for directing a portion of said filtered air to said heating chamber; means for directing the remainder of said filtered air over said take-up and feed reels; a return duct interconnecting the outlet of said solvent recovering chamber with the suction side of said blower to recirculate said drying air; and a return duct adapted to direct the air flowing over said reels to the suction side of said blower for recirculation, whereby a substantially dust-free environment is maintained within said shell by an internally contained air recirculation system.
 3. The apparatus set forth in claim 1 in which said means for removing contaminants from said solvent bath comprises: an offset boiling tank; and one wall of said cleaning chamber having an aperture therein which is in fluid communication with said boiling tank, the lower edge of said aperture defining a spillway for said solvent bath to allow contaminated solvent to continuously spill over into said boiling tank as clean solvent is added to said solvent bath, whereby contaminants may be continuously precipitated from said solvent as the solvent is vaporized in said boiling tank.
 4. The apparatus of claim 3 in which said uLtrasonic cleaning unit further includes: a chilling chamber positioned above said cleaning chamber; refrigerating means secured within said chilling chamber to condense vapor emitted by said boiling tank; a solvent collecting trough positioned within said chilling chamber below said refrigerating means to collect condensed solvent; a reservoir secured to the exterior of said cleaning tank; and a conduit interconnecting said collecting trough and said reservoir.
 5. The apparatus of claim 4 in which said solvent recovery chamber is secured to the exterior of at least one wall of said chilling chamber, said separated solvent recirculating means comprising: a conduit interconnecting said solvent recovery chamber and said reservoir; a conduit interconnecting said reservoir and said boiling tank; a pump; a conduit interconnecting said reservoir and the suction side of said pump; and a conduit interconnecting the pressure side of said pump with said nozzle.
 6. The apparatus of claim 5 wherein said drying chamber is positioned above said cleaning chamber which further includes mechanical stripping means mounted in said drying chamber for mechanically stripping liquid solvent from said film, said mechanically stripped solvent falling back into said ultrasonic cleaning unit for recirculation.
 7. The apparatus of claim 1 in which said strip transport mechanism includes a plurality of rolls, each said roll having a detachable roll mounting assembly comprising: a ball resiliently secured to the central bore of said roll assembly, said ball extending into said bore in its rest position; a shaft having a cross-section complementary to said bore, said shaft having a longitudinal ball guiding groove formed therein extending from its terminal end inward to a recessed nest having a configuration complementary to said ball, whereby said roll may be mounted on said shaft by relative movement between said shaft and roll wherein said ball is guided axially along said ball guiding groove until it is resiliently urged into said nest.
 8. In an apparatus for cleaning strip material having a cleaning chamber containing an ultrasonically agitated solvent bath, an evaporative drying chamber, and means for sequentially passing the strip therethrough, means for forcing a flow of filtered air heated to a temperature greater than the boiling point of said solvent through said drying chamber, means for continuously removing contaminants from said solvent bath which comprises: an offset boiling tank; one wall of said cleaning chamber having an aperture which is in fluid communication with said boiling tank, the lower edge of said aperture defining a spillway for said solvent bath to allow contaminated solvent rinsed from the film to continuously spill over into said boiling tank as solvent is added to said solvent bath, whereby said contaminants may be continuously precipitated from said solvent as the solvent is vaporized in said boiling tank.
 9. In an apparatus for cleaning strip material having a cleaning chamber containing an ultrasonically agitated solvent bath, an evaporative drying chamber for stripping solvent from the strip, and means for sequentially passing the strip therethrough, a chilling chamber positioned between the cleaning chamber and drying chamber having refrigerating means for condensing solvent vapor in said chamber.
 10. The apparatus of claim 9 in which said apparatus further includes a solvent boiling tank, and means providing a passageway for permitting solvent from the cleaning chamber to flow to the boiling tank and permitting vaporized solvent from the boiling tank to flow into the chilling chamber.
 11. The apparatus of claim 9 in which said refrigerating means is disposed along the interior surface of the chilling chamber and a trough extends along the bottom end of the chilling chamber for collecting condensed solvent. 